New citizen Luenoira Leiataua, from Samoa, told those gathered she had arrived in 2011.
She said her two children were born here and she felt it was important to stay in New Zealand to spend her life with her family.
Zimbabwean Chengeto Chaderopa said when he first moved to New Zealand in 2007 he thought it was so cold he was going to die.
Having moved to Rotorua in 2013, Mr Chaderopa said he was thankful for receiving citizenship and grateful to be accepted into the New Zealand way of life.
Rosli Paul and her husband Shibu Joseph Ellimoottil, from India, moved to New Zealand in 2010 from Kuwait. The couple work at Rotorua Hospital.
New Zealand was the best country in the world to raise children, Mr Ellimoottil said, whose two kids joined them during their swearing-in.
"We're grateful to everyone who made this possible."
The Obuyes family, from the Philippines, were reunited in New Zealand in 2009 after Noel Oleo Obuyes had worked in New Zealand for two years previously.
Mr Obuyes thanked people for the support shown to their family.
"This is our land, this is New Zealand, we love New Zealand."
Fellow Filipino Mark Daniel Abellana Alcoseba, who was sworn in alongside Carleen Fe Gabule Ramos and Shellane Gabule Bayron, said while it had been scary arriving in New Zealand not knowing anyone, the people in Rotorua and Aotearoa had made the transition easy.
"We couldn't have picked a better place to call our second home, it is an honour to call ourselves Kiwis."
The ceremony also included items by the council's Waiata Group, and a welcome video message from Governor-General Dame Patsy Reddy and Minister of Internal Affairs Peter Dunne.
New citizens received a book titled Choice and a seedling.
Eight Indians, one Zimbabwean, three Samoans, one Cambodian, eight Filipinos, one Thai, one Nepalese, one South African, one Sri Lankan and six British people became citizens.
